title: Impacts of anthropogenic activity on the ecology of class 1 integrons and integron-associated genes in the environment.
abstract: The impact of human activity on the selection for antibiotic resistance in the environment is largely unknown, although considerable amounts of antibiotics are introduced through domestic wastewater and farm animal waste. Selection for resistance may occur by exposure to antibiotic residues or by co-selection for mobile genetic elements (MGEs) which carry genes of varying activity. Class 1 integrons are genetic elements that carry antibiotic and quaternary ammonium compound (QAC) resistance genes that confer resistance to detergents and biocides. This study aimed to investigate the prevalence and diversity of class 1 integron and integron-associated QAC resistance genes in bacteria associated with industrial waste, sewage sludge and pig slurry. We show that prevalence of class 1 integrons is higher in bacteria exposed to detergents and/or antibiotic residues, specifically in sewage sludge and pig slurry compared with agricultural soils to which these waste products are amended. We also show that QAC resistance genes are more prevalent in the presence of detergents. Studies of class 1 integron prevalence in sewage sludge amended soil showed measurable differences compared with controls. Insertion sequence elements were discovered in integrons from QAC contaminated sediment, acting as powerful promoters likely to upregulate cassette gene expression. On the basis of this data, >1 × 10(19) bacteria carrying class 1 integrons enter the United Kingdom environment by disposal of sewage sludge each year.
authors.affiliation: School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, Warwickshire, UK. w.h.gaze@warwick.ac.uk
authors.forename: William H
authors.initials: WH
authors.lastname: Gaze
authors.forename: Lihong
authors.initials: L
authors.lastname: Zhang
authors.forename: Nouradin A
authors.initials: NA
authors.lastname: Abdouslam
authors.forename: Peter M
authors.initials: PM
authors.lastname: Hawkey
authors.forename: Leo
authors.initials: L
authors.lastname: Calvo-Bado
authors.forename: Jeremy
authors.initials: J
authors.lastname: Royle
authors.forename: Helen
authors.initials: H
authors.lastname: Brown
authors.forename: Susan
authors.initials: S
authors.lastname: Davis
authors.forename: Paul
authors.initials: P
authors.lastname: Kay
authors.forename: Alistair B A
authors.initials: AB
authors.lastname: Boxall
authors.forename: Elizabeth M H
authors.initials: EM
authors.lastname: Wellington
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification; D004251:DNA Transposable Elements; D004202:Disinfectants / Q000378:metabolism; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial; D006802:Human Activities; D007220:Industrial Waste; D032023:Integrons; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*; D012988:Soil Microbiology; D013552:Swine; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004202:Disinfectants; D007220:Industrial Waste; D000644:Quaternary Ammonium Compounds; D012722:Sewage